[Federal Register Volume 87, Number 142 (Tuesday, July 26, 2022)]
[Proposed Rules]
[Pages 44281-44283]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-15854]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
 
 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
 ========================================================================
 

  Federal Register / Vol. 87, No. 142 / Tuesday, July 26, 2022 / 
Proposed Rules  

[[Page 44281]]


=======================================================================
-----------------------------------------------------------------------

NUCLEAR REGULATORY COMMISSION

10 CFR Part 50

[Docket No. PRM-50-122; NRC-2020-0150]


Accident Source Term Methodologies and Corresponding Release 
Fractions

AGENCY: Nuclear Regulatory Commission.

ACTION: Petition for rulemaking; denial.

-----------------------------------------------------------------------

SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) is denying a 
petition for rulemaking dated May 31, 2020, submitted by Brian 
Magnuson. The petitioner requested that the NRC revise its regulations 
to codify the source term methodologies and corresponding release 
fractions recommended in a report issued by Sandia National 
Laboratories; to codify a modified version of draft regulatory guide 
DG-1199, including the source term methodologies recommended in the 
report and the corresponding release fractions; and to account for high 
burnup fuel pellet fragmentation, relocation, and dispersal outside of 
the fuel rod during postulated design basis accidents. The NRC docketed 
the petition on June 18, 2020, and assigned it Docket No. PRM-50-122. 
The NRC is denying the petition because the proposed changes would 
unnecessarily reduce the intended flexibility in the NRC's regulatory 
approach, and they are not necessary to provide reasonable assurance of 
adequate protection of public health and safety.

DATES: The docket for PRM-50-122 is closed on July 26, 2022.

ADDRESSES: Please refer to Docket ID NRC-2020-0150 when contacting the 
NRC about the availability of information for this action. You may 
obtain publicly available information related to this action by any of 
the following methods:
     Federal Rulemaking Website: Go to https://www.regulations.gov and search for Docket ID NRC-2020-0150. Address 
questions about NRC Docket IDs to Dawn Forder; telephone: 301-415-3407; 
email: [email protected]. For technical questions, contact the 
individuals listed in the FOR FURTHER INFORMATION CONTACT section of 
this document.
     NRC Agencywide Documents Access and Management System 
(ADAMS): You may obtain publicly available documents online in the 
ADAMS Public Documents collection at https://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``Begin Web-based ADAMS 
Search.'' For problems with ADAMS, please contact the NRC's Public 
Document Room (PDR) reference staff at 1-800-397-4209, 301-415-4737, or 
by sending an email to [email protected]. For the convenience of the 
reader, instructions about obtaining materials referenced in this 
document are provided in the Availability of Documents section.
     NRC's PDR: You may examine and purchase copies of public 
documents, by appointment, at the NRC's PDR, Room P1 B35, One White 
Flint North, 11555 Rockville Pike, Rockville, Maryland 20852. To make 
an appointment to visit the PDR, please send an email to 
[email protected] or call 1-800-397-4209 or 301-4154737, between 8 
a.m. and 4 p.m. (ET), Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Adakou Foli, Office of Nuclear Reactor 
Regulation; telephone: 301-415-1984; email: [email protected], or 
Solomon Sahle, Office of Nuclear Material Safety and Safeguards; 
telephone: 301-415-3781; email: [email protected]. Both are staff 
of the U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001.

SUPPLEMENTARY INFORMATION:

Table of Contents:

I. The Petition
II. Public Comments on the Petition
III. Reasons for Denial
IV. Availability of Documents
V. Conclusion

I. The Petition

    Section 2.802 of title 10 of the Code of Federal Regulations (10 
CFR), ``Petition for rulemaking--requirements for filing,'' provides an 
opportunity for any interested person to petition the Commission to 
issue, amend, or rescind any regulation. On May 31, 2020, the NRC 
received a petition for rulemaking (PRM) from Brian Magnuson. The 
petitioner requested that the NRC amend its regulations in Sec.  50.67, 
``Accident source term,'' to codify the following:
     the source term methodologies recommended in the Sandia 
National Laboratories report SAND2008-6601, ``Analysis of Main Steam 
Isolation Valve Leakage in Design Basis Accidents Using MELCOR 1.8.6 
and RADTRAD,'' issued October 2008; and
     a modified version of draft regulatory guide (DG) DG-1199, 
``Alternative Radiological Source Terms for Evaluating Design Basis 
Accidents at Nuclear Power Reactors,'' issued October 2009, that would 
include the source term methodologies recommended in SAND2008-6601 and 
the corresponding release fractions.
    The petition also requested that the NRC revise Sec.  50.67 to 
account for high burnup fuel pellet fragmentation, relocation, and 
dispersal outside of the fuel rod during postulated design-basis 
accidents.
    The DG-1199 was a proposed revision to Regulatory Guide (RG) 1.183, 
``Alternative Radiological Source Terms for Evaluating Design Basis 
Accidents at Nuclear Power Reactors,'' Revision 0, issued July 2000, 
and was not finalized as an update to RG 1.183. After the issuance of 
DG-1199 for public comment, the staff received a number of public 
comments and spent significant efforts in addressing the comments, 
including resolving different NRC staff views on the approach in 
addressing certain comments. The efforts included soliciting an 
independent review of certain aspects of the DG-1199 performed by 
Sandia National Laboratories. In 2017, the NRC received the final 
responses from Sandia National Laboratories associated with their 
independent review.
    In late 2020, the NRC resumed RG 1.183 revision efforts after 
considering a significant amount of insight gained since the initial 
issuance of the DG-1199, including the 2017 Sandia National 
Laboratories responses and research pertaining to state-of-the-art 
source term knowledge, such as the fuel fragmentation, relocation, and 
dispersal. The planned revision will include this information and also 
will update RG 1.183 to support accident tolerant fuel

[[Page 44282]]

and higher enrichment and burnup levels.
    The petition identified concerns with the NRC guidance used to 
calculate radiological doses to comply with the regulations in Sec.  
50.67, stating that (1) the current NRC guidance in RG 1.183 is 
``conceptually inaccurate'' and ``nonconservative'' based on SAND2008-
6601, and (2) nuclear power plants use varying regulatory guidance 
(e.g., Technical Information Document (TID)-14844, ``Calculation of 
Distance Factors for Power and Test Reactor Sites,'' issued March 1962; 
NUREG-1465, ``Accident Source Terms for Light-Water Nuclear Power 
Plants,'' issued February 1995; and RG 1.183) that relies on different 
source term methodologies and corresponding release fractions to 
satisfy the same regulations. The petition argued that due to these 
concerns, many nuclear power plants are ``likely not in compliance with 
some, or all of their applicable regulations and requirements, which 
ultimately protect people and the environment.'' The petitioner stated 
that the proposed revision to Sec.  50.67 would eliminate 
inconsistences resulting from the use of different source term 
methodologies and release fractions and would provide the requisite 
means to ensure compliance with the underlying regulations.

II. Public Comments on the Petition

    On August 24, 2020 (85 FR 52058), the NRC published a notice of 
docketing of PRM-50-122 and a request for public comment on the PRM in 
the Federal Register. The public comment period closed on November 9, 
2020. The NRC received two comment submissions: (1) one commenter (the 
petitioner) provided supplemental information in support of the 
petition, and (2) one commenter (an NRC staff member acting in his 
personal capacity) opposed the petition. This latter comment was 
withdrawn from the petition docket because it included non-public 
information. The NRC reviewed the comments in making its decision on 
the petition.
    A summary of the comment from the petitioner and the NRC's response 
follows. The comment is available as indicated in the Availability of 
Documents section of this document.
    Comment: The petitioner provided additional concerns related to RG 
1.183, Revision 0, such as the treatment of uncertainties in the source 
terms and the behavior of main steam isolation valve leakage. He stated 
that such issues provide additional justification for codifying a 
modified version of DG-1199 in Sec.  50.67.
    NRC Response: As discussed in more detail in the Reasons for Denial 
section of this document, the NRC disagrees with the comment, and finds 
that RG 1.183, Revision 0 continues to provide an acceptable method to 
address design-basis accident radiological consequences to comply with 
the applicable regulations. With regard to the continued acceptability 
of RG 1.183, Revision 0, additional information also appears in the 
Differing Professional Opinion case file DPO-2020-002, available as 
indicated in the Availability of Documents section of this document.

III. Reasons for Denial

    The NRC is denying the petition because the requested changes would 
unnecessarily reduce the intended flexibility inherent in Sec.  50.67 
and the NRC's overall regulatory approach in the area of design-basis 
accident radiological consequence analyses. The NRC's current 
regulations and oversight activities continue to provide reasonable 
assurance of adequate protection of public health and safety.
    Codifying a specific source term methodology and corresponding 
release fractions in Sec.  50.67 would unnecessarily limit options for 
meeting the requirements, whereas Sec.  50.67 currently allows the use 
of alternative sufficient methods of compliance. A detailed approach 
for determining source term is provided in RG 1.183, Revision 0, which 
describes one way to meet the requirements in Sec.  50.67.
    In Sec.  50.67, the NRC provides requirements on the acceptable 
dose criteria from the design-basis analyses based upon a major 
accident assumed to result in substantial meltdown of the core with 
subsequent release of appreciable quantities of fission products (see 
Sec.  50.67; see also TID-14844 and NUREG-1465). The regulatory 
approach of using design-basis accidents and applying performance-based 
regulatory requirements is consistent with the approach provided in 
other NRC regulations, including Sec.  50.46, ``Acceptance criteria for 
emergency core cooling systems for lightwater nuclear power reactors,'' 
and Sec.  50.65, ``Requirements for monitoring the effectiveness of 
maintenance at nuclear power plants.'' Furthermore, when Sec.  50.67 
was promulgated, the NRC did not include a defined methodology for 
demonstrating compliance, consistent with other regulations related to 
radiological reactor siting criteria, such as Sec.  100.11, 
``Determination of exclusion area, low population zone, and population 
center distance,'' and Sec.  50.34, ``Contents of applications; 
technical information.'' Instead, Sec.  50.67 allows changes to the 
defined source term or the development of other technically sound 
source term values without requiring additional rulemaking, and the NRC 
still finds this approach to be appropriate. Therefore, instead of 
codifying a particular source term methodology, the NRC used NUREG-1465 
and other technical information to develop RG 1.183 to provide one 
acceptable methodology for complying with Sec.  50.67, but not the only 
one. This has provided the NRC and the nuclear industry with both 
regulatory clarity and the flexibility to consider and incorporate new 
research and technical advancements while continuing to ensure safety. 
The approach in Sec.  50.67 is to provide flexibility in applying basic 
principles to new situations and the use of evolving methods of 
analyses in the licensing process, and not to include prescriptive 
methodology in the regulation. This approach reflects the philosophy 
that the regulation only contains the high-level requirements and that 
the technical details are contained in guidance and updated, as 
appropriate, to reflect current knowledge. The NRC finds that Sec.  
50.67 continues to provide reasonable assurance of adequate protection 
and safety given new technologies and continued lessons learned. For 
example, the current Sec.  50.67 requires that the application contain 
an evaluation of the consequences of applicable design basis accidents. 
In addition, Sec.  50.90 requires that applications for license 
amendments fully describe the desired changes. Therefore, applicants 
and licensees are required to address significant changes to the fuel 
design such as increases to fuel burnup limits and potential fuel 
fragmentation, relocation, and dispersal issues, and the NRC will only 
approve an amendment if the applicant's analysis demonstrates with 
reasonable assurance that dose values are met, consistent with the 
agency's process.

IV. Availability of Documents

    The documents identified in the following table are available to 
interested persons through one or more of the following methods, as 
indicated.

[[Page 44283]]



----------------------------------------------------------------------------------------------------------------
                                                                                                ADAMS  Accession
                                                                                                 No. or Federal
                         Document                                          Date                Register citation
                                                                                                  or  web site
----------------------------------------------------------------------------------------------------------------
PRM-50-122, ``Petition to Amend 10 CFR 50.67, Accident      May 31, 2020.....................        ML20170B161
 Source Term, to Include Methodologies and Release
 Fractions''.
DG-1199, ``Alternative Radiological Source Terms for        October 2009.....................        ML090960464
 Evaluating Design Basis Accidents at Nuclear Power
 Reactors''.
SAND2008-6601, ``Analysis of Main Steam Isolation Valve     October 2008.....................        ML083180196
 Leakage in Design Basis Accidents Using MELCOR 1.8.6 and
 RADTRAD''.
RG 1.183, ``Alternative Radiological Source Terms for       July 2000........................        ML003716792
 Evaluating Design Basis Accidents at Nuclear Power
 Reactors,'' Revision 0.
NUREG-1465, ``Accident Source Terms for Light-Water         February 1995....................        ML041040063
 Nuclear Power Plants''.
TID-14844, ``Calculation of Distance Factors for Power and  March 23, 1962...................        ML021720780
 Test Reactors''.
Accident Source Term Methodologies and Corresponding        August 24, 2020..................        85 FR 52058
 Release Fractions; Notice of Docketing and Request for
 Comment.
Comment (002) of Brian Magnuson on PRM-50-122--Accident     November 8, 2020.................        ML20330A276
 Source Term Methodologies and Corresponding Release
 Fractions.
Differing Professional Opinion (DPO) Case File for DPO-     March 8, 2021....................        ML21067A645
 2020-002.
----------------------------------------------------------------------------------------------------------------

V. Conclusion

    For the reasons cited in this document, the NRC is denying PRM-50-
122. The current requirements in Sec.  50.67 continue to provide 
reasonable assurance of adequate protection of public health and safety 
and should not be revised as proposed in the PRM.

    Dated: July 19, 2022.

    For the Nuclear Regulatory Commission.
Brooke P. Clark,
Secretary of the Commission.
[FR Doc. 2022-15854 Filed 7-25-22; 8:45 am]
BILLING CODE 7590-01-P